Re: [PATCH] Enable GCC support for AMX

[Kirill Yukhin <kirill.yukhin@gmail.com>]

Hello,

On 03 сен 08:17, H.J. Lu wrote:
> On Thu, Sep 3, 2020 at 8:08 AM Kirill Yukhin via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
> >
> > Hello,
> >
> > On 06 июл 09:58, Hongyu Wang via Gcc-patches wrote:
> > > Hi:
> > >
> > > This patch is about to support Intel Advanced Matrix Extensions (AMX)
> > > which will be enabled in GLC.
> > >
> > > AMX is a new 64-bit programming paradigm consisting of two
> > > compo nents: a set of 2-dimensional registers (tiles) representing
> > > sub-arrays from a larger 2-dimensional memory image,
> > > and an accelerator able to operate on tiles
> > >
> > > Supported instructions are
> > >
> > > AMX-TILE:ldtilecfg/sttilecfg/tileloadd/tileloaddt1/tilezero/tilerelease
> > > AMX-INT8:tdpbssd/tdpbsud/tdpbusd/tdpbuud
> > > AMX-BF16:tdpbf16ps
> > >
> > > The intrinsics adopts constant tile register number as its input parameters.
> > >
> > > For detailed information, please refer to
> > > https://software.intel.com/content/dam/develop/public/us/en/documents/architecture-instruction-set-extensions-programming-reference.pdf
> > >
> > > Bootstrap ok, regression test on i386/x86 backend is ok.
> > >
> > > OK for master?
> >
> > I was trying to apply your patch to recent master and got
> > compilation error:
> >
> > g++ -std=gnu++11  -fno-PIE -c   -g -O2 -DIN_GCC     -fno-exceptions -fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-narrowi
> > ng -Wwrite-strings -Wcast-qual -Wmissing-format-attribute -Woverloaded-virtual -pedantic -Wno-long-long -Wno-variadic-macros -Wn
> > o-overlength-strings -fno-common  -DHAVE_CONFIG_H -I. -I. -I/export/kyukhin/gcc/src/gcc -I/export/kyukhin/gcc/src/gcc/. -I/expor
> > t/kyukhin/gcc/src/gcc/../include -I/export/kyukhin/gcc/src/gcc/../libcpp/include  -I/export/kyukhin/gcc/src/gcc/../libdecnumber
> > -I/export/kyukhin/gcc/src/gcc/../libdecnumber/bid -I../libdecnumber -I/export/kyukhin/gcc/src/gcc/../libbacktrace   -o i386-opti
> > ons.o -MT i386-options.o -MMD -MP -MF ./.deps/i386-options.TPo /export/kyukhin/gcc/src/gcc/config/i386/i386-options.c
> > /export/kyukhin/gcc/src/gcc/config/i386/i386-options.c: In function ‘bool ix86_option_override_internal(bool, gcc_options*, gcc_
> > options*)’:
> > /export/kyukhin/gcc/src/gcc/config/i386/i386-options.c:2263:41: error: ‘PTA_AMX_TILE’ was not declared in this scope
> >   if (((processor_alias_table[i].flags & PTA_AMX_TILE) != 0)
> >                                          ^
> > /export/kyukhin/gcc/src/gcc/config/i386/i386-options.c:2267:41: error: ‘PTA_AMX_INT8’ was not declared in this scope
> >   if (((processor_alias_table[i].flags & PTA_AMX_INT8) != 0)
> >                                          ^
> > /export/kyukhin/gcc/src/gcc/config/i386/i386-options.c:2271:41: error: ‘PTA_AMX_BF16’ was not declared in this scope
> >   if (((processor_alias_table[i].flags & PTA_AMX_BF16) != 0)
> >
> > Could you please fix that?
> 
> Here is the rebased patch against
> 
> commit 3c219134152f645103f2fcd50735b177ccd76cde
> Author: Jonathan Wakely <jwakely@redhat.com>
> Date:   Thu Sep 3 12:38:50 2020 +0100
> 
>     libstdc++: Optimise GCD algorithms
> 
> Thanks.
> 
> -- 
> H.J.

> diff --git a/gcc/config.gcc b/gcc/config.gcc
> index 797f0ad5edd..d0e59e86a5c 100644
> --- a/gcc/config.gcc
> +++ b/gcc/config.gcc
> @@ -412,7 +412,7 @@ i[34567]86-*-*)
>  		       waitpkgintrin.h cldemoteintrin.h avx512bf16vlintrin.h
>  		       avx512bf16intrin.h enqcmdintrin.h serializeintrin.h
>  		       avx512vp2intersectintrin.h avx512vp2intersectvlintrin.h
> -		       tsxldtrkintrin.h"
> +		       tsxldtrkintrin.h amxtileintrin.h amxint8intrin.h amxbf16intrin.h"

Line more than 80 chars.

>  	;;
>  x86_64-*-*)
>  	cpu_type=i386
> @@ -447,7 +447,7 @@ x86_64-*-*)
>  		       waitpkgintrin.h cldemoteintrin.h avx512bf16vlintrin.h
>  		       avx512bf16intrin.h enqcmdintrin.h serializeintrin.h
>  		       avx512vp2intersectintrin.h avx512vp2intersectvlintrin.h
> -		       tsxldtrkintrin.h"
> +		       tsxldtrkintrin.h amxtileintrin.h amxint8intrin.h amxbf16intrin.h"

Ditto.

> diff --git a/gcc/config/i386/amxbf16intrin.h b/gcc/config/i386/amxbf16intrin.h
> new file mode 100644
> index 00000000000..df0e2262d50
> --- /dev/null
> +++ b/gcc/config/i386/amxbf16intrin.h
> @@ -0,0 +1,25 @@
> +#if !defined _IMMINTRIN_H_INCLUDED
> +#error "Never use <amxbf16intrin.h> directly; include <immintrin.h> instead."
> +#endif
> +
> +#ifndef _AMXBF16INTRIN_H_INCLUDED
> +#define _AMXBF16INTRIN_H_INCLUDED
> +
> +#if !defined(__AMX_BF16__)
> +#pragma GCC push_options
> +#pragma GCC target("amx-bf16")
> +#define __DISABLE_AMX_BF16__
> +#endif /* __AMX_BF16__ */
> +
> +#if defined(__x86_64__) && defined(__AMX_BF16__)
> +#define _tile_dpbf16ps(dst,src1,src2)					\
> +  __asm__ volatile\
> +  ("{tdpbf16ps\t%%tmm"#src2", %%tmm"#src1", %%tmm"#dst"|tdpbf16ps\t%%tmm"#dst", %%tmm"#src1", %%tmm"#src2"}" ::)
> +#endif

I hope in future we'll replace it with unspecs at least...

> diff --git a/gcc/config/i386/i386.opt b/gcc/config/i386/i386.opt
> index c9f7195d423..9389dc24948 100644
> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> index bca8c856dc8..a46e31f5862 100644
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -1357,6 +1357,7 @@ See RS/6000 and PowerPC Options.
>  -mvpclmulqdq  -mavx512bitalg  -mmovdiri  -mmovdir64b  -mavx512vpopcntdq @gol
>  -mavx5124fmaps  -mavx512vnni  -mavx5124vnniw  -mprfchw  -mrdpid @gol
>  -mrdseed  -msgx -mavx512vp2intersect -mserialize -mtsxldtrk@gol
> +-mamx-tile -mamx-int8 -mamx-bf16@gol

Add space please.

> diff --git a/gcc/testsuite/gcc.target/i386/amxbf16-asmintel-2.c b/gcc/testsuite/gcc.target/i386/amxbf16-asmintel-2.c
> new file mode 100644
> index 00000000000..605a44df3f8
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/amxbf16-asmintel-2.c
> @@ -0,0 +1,4 @@
> +/* { dg-do assemble { target { ! ia32 } } } */
> +/* { dg-options "-O2 -mamx-bf16 -masm=intel" } */
> +/* { dg-require-effective-target amx_bf16 } */
> +#include"amxbf16-asmintel-1.c"

I didn't get it. We ususally use second tescase to actually execute
it and (well, a little) verify that semantics is ok. E.g. that
operands order is correct. Could you please do that?
This applies to all *-2.c cases.
I've checked and looks like public SDE simulator supports AMX.

--
K